According to the United Nations, in 2015, 663 million people lacked an improved water supply, and contaminated water resulted in more than ½ million deaths annually. The United Nations expects 14% of the world's population to encounter water scarcity by 2025. Sustaining the availability and quality of water with minimal cost and environmental impact is one of the greatest challenges facing humanity.
However, the largest water resource is saltwater derived from the seas and oceans. Such saltwater is undrinkable in natural form, but can be desalinated and decontaminated to provide potable water. Currently, about 1% of the world's population is dependent on desalinated water. The interest in desalination will likely grow.
Current desalination and decontamination technologies are costly, utilizing considerable energy input. For example, desalination methods using distillation use a considerable amount of energy to facilitate the evaporation of water from a salt water source. Conventional reverse osmosis can also be energy demanding, although less so than distillation, because the saltwater source is pressurized to overcome osmotic pressures across semipermeable membranes. As such, the economics of conventional desalination methods limit their widespread application.
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